Vacuum waste systems are generally known in the art for use in transportation vehicles such as airlines. Vacuum waste systems typically comprise a waste receptacle connected by a vacuum line to a waste tank. When a flush valve connected to the waste receptacle opens, the contents of the waste receptacle are removed by differential pressure to the waste tank. Generally, rinse fluid is delivered to the waste receptacle via nozzles to assist in the ease of waste removal and to clean the walls of the waste receptacle.
Conventional rinse valves for controlling the flow of aqueous rinse fluid to vacuum waste receptacles are generally known. Rinse valves are actuated when a command is initiated from a user input device such as a flush button. Such rinse valves often use solenoid actuated armature arrangements to control the flow of rinse fluid to the waste receptacle.
In typical designs for solenoid-actuated rinse valves the solenoid armature is disposed directly in the main flow path of the rinse fluid. Such prior systems present reliability problems because the substantial wetting of the armature with the rinse fluid combined with the draining of rinse fluid from adjacent the armature during servicing causes the build-up of mineral deposits on the surfaces of the armature and its housing. The friction produced by this mineral build-up initially tends to cause higher current draw to the solenoid in order to move the armature over a deposit-roughened surface. Over time, the mineral build-up may become so great that the armature may seize in the open or closed position. A rinse valve with an armature seized in the closed position will not provide rinse fluid to a toilet while a rinse valve with an armature seized in the open position will cause flooding of the lavatory area. In addition, bearing and shearing stresses on the armature and housing surfaces due to friction from mineral build-up contribute to galling and flaking of surface plating as well as contamination from micro-particles. A need therefore exists for an improved rinse valve and method for controlling the flow of rinse fluid to vacuum waste receptacles such as vacuum toilets.
Under certain circumstances a rinse valve may be exposed to very cold temperatures for a prolonged period of time. If prolonged cold exposure and inactivity occur, and the rinse fluid is not drained or is incompletely drained from the rinse valve, it is not uncommon for frozen rinse fluid to form within the rinse valve. In a conventional rinse valve, the expansion of the frozen rinse fluid inside of the valve may crack or otherwise damage the valve. A need therefore exists for an improved rinse valve and method for providing protection against damage caused by rinse fluid freezing within the rinse valve.